Artificial silk and the manufacture thereof



Patented July 15, 1930 UNITED STATE PATENT OFFICE WILLIAM H. FURNESS, OFNATIONAL PARK, NEW JERSEY, ASSIGNOR TO CELLOGILK COMPANY, OFPHILADELPHIA, PENNSYLVANIA, A CORPORATION OF DELAWARE ARTIFICIAL SILKAND THE MANUFACTUBE THEREOF Ho Drawing. Application filed April 6,

This invention relates to artificial silk and the manufacture thereof,and its nature, objects and advantages will be best appreciated from thefollowing.

Considered from the standpoint of the fabric to be manufacturedtherefrom, the thread of my invention is composed of non-adherent,flexible filaments having the transparency and luster and fineness ofnatural silk, giving the fabric made therefrom the hand, drape, softnessand other properties which characterize a natural silk product.

From the standpoint of manufacture into fabric, the silk has thefollowing advantages. It is characterized by low elongation over theentire range of load both wet and dry, and has substantially the sameelongation (from 4 to 10%) in the wet as in the dry state (65%atmospheric humidity) and at any intermediate degree of relativehumidity normally obtaining. In this connection, the strength-elongationcurve of the silk in the dry state, as shown on the standard,

Serigraph chart, is substantially parallel to the base line for overhalf the breaking load, with no yield points, the rise in the curve asit approaches the breaking point being gentle and uniform. Theelongation curve in the wet state is approximately parallel to that ofthe dry, with no yield points. It is, therefore, possible commerciallyto weave, wind,

knit, twist, size, or otherwise manipulate or treat the thread in themanufacturing operations without appreciable change in dimension orother physical properties. This makes it possible to operate on a cottonyarn basis without producing defective cloth. Italso eliminates much ofthe apparatus, certain of the operations, and reduces the number ofoperatives and care required at present in the manufacture of fabricfrom artificial silk. In addition to the economies in plant investment,labor, etc., thus effected, it is possible, if desired, to speed up themill operations and still further reduce costs.

It will be apparent that the properties of low elongation and samenessof elongation, both wet and dry, will ensure the production of a fabricwhich will Withstand all manipulations wet or dry, including washing,dye- 1927. Serial No. 181,814.

ing, finishing, etc., without elongation or permanent distortion. Inaddition, the silk cannot elongate during fabrication so as to becomerigid or change its refractive index which would produce a shiner due tothis cause.

The silk, therefore, resembles natural silk, but can be Worked likecotton yarn, and, among other things, differs from all yarns in that itselongation-humidity curve is straight and parallel to the base forsubstantially all degrees of relative humidity. Its dry strength isapproximately 70% higher than cotton yarn of equivalent size.

The foregoing and other advantages will be readily appreciated by thoseskilled in the textile art, but, in addition, the high dry strength,flexibility, elasticity, and elongation characteristics of the silkconstitute a combination of properties which makes it possible to employthe fabric for new uses, such as for cord tires, air-craft fabrics,water-proofed fabrics, etc.

I believe the unique physical properties of the thread are to beattributed to the fact that I employ cellulose solutions of suchcharacter that the original crystallite chains of the cellulose aredispersed in the liquid in approximately their original form, and thatthe cells of the gel precipitated therefrom during the formation of thefilaments of the thread are of such character and disposition that bystretching they may be collapsed and elongated with the crystallitechains substantially intact and largely extending longitudinally of thethread in overlapping relation and with the inter-cellular spaceslargely eliminated or reduced; the properties thus secured beingretained throughout the remaining operations.

In consequence of the foregoing I obtain, on the one hand, the hightensile strength hereinbefore referred to, and, on the other hand,remove the extensibility due to the structure formed by theprecipitation of the gell in the formation of the filaments to the pointwhere the thread has the elongation characteristics set forth.

In the making of the silk of my invention I prefer to proceed asfollows: I prepare a very concentrated solution of pure copper hydrate,ammonia and cellulose, preferably in about minimum dissolvingproportions. By proceeding in this manner I keep down the quantity ofammonia required to a point where its detrimental ell'ect on thecellulose is negligible. I then dilute the solution thus prepared with asubstantially inert liquid such as water, employing an amount thereofsuch that the resultant solution may be directlyspun into aprecipitating bath, such as a caustic bath, with the production offilaments, which, in relation to the spinneret orifices, are very small,and which are practically immediately and completely solidified so thatwhen they merge into the thread they I do not adhere but remain readilyseparable.

I have found that the best results are ob tained when the initialsolution is of approximately fifteen to twenty percent cellu' scribed,and that the structure of the gel is probably in the form of large thinwalled cells, the Walls of which are constituted by the crystallitechains in substantially intact condition. Also, with this solution, I amenabled, if desired, to form by direct spinning gas distinguished fromthe well known stretch spinning method) filaments as fine as those ofnatural silk through relatively coarse spinneret holes. For example, Imay directly spinfilaments as fineas one and onehalf denier and belowfrom orifices as large as four and one-half to five thousandths of aninch. The thread may be spun without fila ment breakage very rapidly-ashigh as 80 or 90 yards per minute, which eifects a great ecoiiom in costof production-orvery slowly.as ow as 10 yards per minute'which securesadvantages in doffiing which will be pointed out.

I have mentioned that a four percent cellu- .losesolution is preferredas giving the best results, particularly as to strength of the thread.Solutions lower in cellulose content work approximately as well, butapproach instability, and solutions of greater content do not produce asstrong a thread. I prefer not to exceed a five percent solution nor touse less than a three and one-half percent solution.

A further advantage is that age does not affect the solution, nor do thesolutions have to be aged.

The thread which has been precipitated is then passed over a drawingwheel and around a second drawing wheel of larger diameter, thedifference in diameter depending upon the size of spool employed, speedof operation, etc. From the second and larger wheel the thread is. ledto a cap twister and is wound and twisted on to a spool with theemployment of a loop or balloon at the cap. The thread is put undertension and stretched during this operation by the larger or stretchingwheel and by the centrifugal force of the loop. This stretching which isgiven to the thread is believed to elongate the cells and form them intothe shape of overlapping fibers running lengthwise of the thread, withthe intercellular space practically eliminated or-at least greatlyreduced. The tension should be sulficient to impart a stretch which willremove extensibility to the point hereinbefore mentioned. The stretchgiven is retained by the thread on the spool.

For reasons of mechanical expediency, I

prefer to operate the spool spindle and also the cap at constant speed,and to the endthat the thread shall not be injured, and that it may belaid on the spool of uniform denier the cap at a speed slower than thespeed of the spindle and at approximately the speed of the balloon ofthe yarn. In consequence of this when starting a spool, the onlyrelative movement as between the cap and the thread is the inwardmovement of the thread. As the thread is laid up and the diameter of thespool increases, the cap lags slightly behind the balloon of the yarn,but the relative movement as between the cap and the yarn is now smalland in a direction approximately parallel to the fibers of the yarn. Inconsequence of this, there is no liability of damage to the yarn, and,for all practical purposes, the tension is solely that due to thecentrifugal force referred to, but because of variations due to increasein diameter of the spool which might throughout, I proceed as follows: Ioperate Therefore, I am able to reduce the speed of the spindle, thecap, the drawing wheel, and the extrusion pump. By thus reducing thespeed of production of the thread, I may break the thread after itpasses over the second wheel and allow it to accumulate on a suitableplate without material loss while the filled spool is being doifed and anew spool insorted, and may easily start the thread and restore normaldrawing conditions. I prefer to simultaneously reduce the speed of thespindle, the cap, the drawing wheel, and the extrusion ump, in order tomake even at the slow spee s necessary for dofiing, a thread ofsubstantially the same size as before, so that I may be able to startthe thread on the new spool, an appreciable difference in the size ofthe thread making it impossible to do so.

To facilitate further treatment of thethread I prefer that the spoolsshall have a removable head, and I take the filled spool, remove thehead, and unwind the thread from the spool in the direction of theunheaded end, subjecting the thread, as it is being unwound, to awashing medium applied so that the successive layers, as they areexposed by unwinding, are subjected thereto. This I prefer to do byimmersing the spool in a bath. The bath contains a small amount ofcaustic soda or other electrolyte which prevents the softening of thethread, or, stated in other words. the bath is one in which the gel isstahis. The bath removes the greater proportion of the caustic soda andother water soluble materials of the thread, the unwinding and resultantexposure of successive layers being very effective for this purpose. Asthe thread is being unwound and leaves the bath, it is drawn through anacid bath which converts the copper hydroxide into a soluble copper saltand also liberates the combined water of the cellulose hydrate, wherebythe thread is greatly reduced in diameter (deflated). The deflatedthread is wound upon a spool or cylinder. preferably revolving in anacid bath. It will, of course, be undersood that as rapid- IV as thethread is being unwound. it is drawn through the acid bath and woundupon the cylinder, all of these operations being carried on with thethread under sufiicient tension to maintain the stretch which waspreviously inder, and, in order that the cake of thread may be uniformlywashed, I prefer to so wind it that the layers are of successivelydiminishing length, which will produce a cake, the edge or end portionsof which taper with the same exposure and the same permeability of thoseportions as has the main body portion of the cake. Thus, the cakeisuniformly washed throughout its length. The washing is facilitated byperforating the cylinder.

As one means for producing a. cake of the characteristics hereinbeforedescribed, I may employ a cylinder or a spool, the spindle por tion ofwhich is convcxed or slanted at the edges.

Owing to the fact that the thread is completely deflated before windingon the cylinder, the change in physical dimension durder a very largeamount of thread-15,000

yards or upwards of 150 denier size-which effects further economy andsimplicity. It will be seen that the conditions are such that the threaddoes not become injured nor the fibers broken.

The washed and dried thread is now ready to soften, and, as one meansfor accomplishmg this, I unwind it from the cylinder and wind it upon atwisting spool for the purpose of imparting a final twisting which, dueto the change in position of the fibers produced, softens the thread.This is possible because of the non-adherent character of the fibers. Toaccomplish this the cylinder on which the thread has been washed anddried is placed upon two rollers, one or both of which are driven, thethread, as it leaves the cylinder, preferably passing ovcr one of therollers. By driving the cylinder in this fashion, I am enabled to lay upthe thread on a twisting spool from the relatively heavy cylinderwithcut removing the remaining extensibility. An advantage incident tocausing the thread to pass over one of the rollers is that this rollermay be kept wet so as to size or otherwise treat the thread. By thisprocedure I eliminate the skeining operations heretofore required forsoftening and treating the washed and dried thread, and I am enabled tomarket the product on the spool. This not only effects an economy in themanufacturing operations, but also an economy for the mill ultimatelyusing the thread, besides which the damage which frequently resulted tothe thread in the handling and shipping of skeins is entirely obviated.

It might here be mentioned that the thread may be twisted and wound inthe wet state without distortion or loss of flexibility.

Among other advantages the silk may be doubled with cotton yarn in suchmanner that the strength ofthe yarn is approximately equal to thecombined strength of the two threads which, due to the marked differencein the elongation between cotton yarn and the heretofore manufacturedsilk, has not been possible.

The apparatus herein referred to is illustrated and claimed in mycopending applications Serial Nos. 239,401, 239,402, 239,403, 239,404,239,405 filed December 12, 1927.

The drawing mechanism, the driving mechanism, the differential cap speeddevice, and the apparatus for laying .up cakes are not specificallyclaimed herein, as the same constit-ute subject matter respectivelyclaimed in No claim is herein made to the specific method of laying upcakes, as this forms subject matter of application No. 239,405.

strength curve, wet and dry.

.3. As a new article of manufacture, artificial silk thread havingapproximately the same elongation for all degrees of relative humiditynormally obtaining.

4. As a new article of manufacture, artificial silk thread having a lowelongation over a wide range of load.

5. As a new article of manufacture, artificial silk thread having a lowelongation over.

a wide range of load and approximately the same elongation wet as dry.

6. As a new article of manufacture, artificial silk threadhaving a highinitial resistance to elongation.

7. As a new article of manufacture, artificial silk thread having noappreciable yield points in its elongation-strength curve, wet and dry.J

8. As a new article of manufacture, a direct spun fine filamentcupro-ammonium artificial silk thread of the order of the denier ofnatural silk.

9. As a new article of manufacture, a cupro-ammonium artificial silkthread spun froma cellulose solution containing an amount of .inertliquid such that filament-s of the order l'ul of natural silk may bedirectly spun.

10. As a new article of manufacture, an artificial silk thread spun froma cellulose solution containing an amount of inert liquid such thatfilaments of the order of natural silk may be directly spun fromrelatively large orifices. g

11. As a new article of manufacture, an artificial silk thread spun froma cellulose solution containing an amount of inert liquid such as toproduce a gel of coarse thin walled cell structure, the cells of whichunder tension may be elongated snfiiciently to ensure a flexible threadcharacterized by marked resistance to further elongation.

12. As a new article of manufacture, an artificial silk thread spun froma cellulose solution containing an amount of inert liquid such as toproduce a gel of coarse thin walled cell structure.

13. As a new article of manufacture, fine filament artificial silkthread-spun from a cupro-ammonium solution of cellulose so difollowinglute that the gel precipitated in filament form is immediately andcompletely solidified before the filaments mer e whereby the filamentsremain in individua readily separable form. a

14. As a new article of manufacture, artificial silk thread precipitatedfrom a solution in which the crystallite chain structure of the originalcellulose is retained.

15. As a new article of manufacture, artificial silk thread precipitatedfrom a solution in which the crystallite chain structure of the originalcellulose is retained with the cell structure elongated and collapsed.

16.- As a new article of manufacture, artificial silk thread probably inwhich the crystallite chain structure of the original cellulose isretained and probably in which the cells have been elongated andcollapsed with the crystallite chains largely extending lengthwise ofthethread characterized by the sile strengt 1 both wet and dry; resistanceto elongation over a wide range of load; approximately the sameelongation wet as dry and at all intermediate degrees of humidity; andthe filaments of which do not adhere one to the other.

17. As a new article of manufacture, arti ficial silk thread spun from asolution made by diluting with water a solution of copper hydroxide,ammonia and cellulose in approximately minimum dissolving proportions.

18. As a new article of manufacture, artificial silk thread spun from asolution made by diluting with water a solution of copper hydroxide,ammonia and cellulose in approximately minimum dissolving proportions,the dilution being such that the final solution contains about 4% ofcellulose.

19., As a new article of manufacture, artificial silk thread which inthe process of manufacture is stretched to remove the extensibilitywhereby the product has approximately the same extensibility wet asdry..

20. As a new article of manufacture, artificial silk thread which in theprocess of manufacture has had removed therefrom its extensibility tothe point where the product has approximately the same elongation wet asa cotton basis without producing defective cloth. I

roperties-flexibility; high ten- 23. As a new article of manufacture,artificial silk thread which in the process of manufacture, has hadremoved therefrom the extensibility to the point where the product isresistant to elongation over a range of load which permits ofmanufacturing operations such as winding, weaving, twisting, etc.,without alteration in denier.

24. As a new article of manufacture, artificial silk thread treated inthe manufacture to remove extensibility to the point where the thread isso resistant to elongation even while wet that the thread may be sizedin a manner customary tocotton yarn and fabricated without substantialdistortion.

25. As a new article of manufacture, artificia'l silk thread which inthe process of manufacture has had removed therefrom its extensibilityto the point where the strength elongation relation curve of the productis substantially fiat and parallel to the base line until the breakingpoint is approached and without yield points.

26. As a new article of manufacture, artificial silk thread which in theprocess of manufacture has had removed therefrom its extensibility tothe point where the elongationhumidity curve of the product is straightand parallel the base for substantially all degrees of humidity.

27. As a new article of manufacture, artificial silk thread which in theprocess of manufacture has had removed therefrom its extensibility tothe point where the elongationstrength curve in the wet state is withoutappreciable yield points.

28. As a new article of manufacture, artificial thread silk in which theextensibility due to the precipitation of a cellulose solution in theform of a gel is largely removed in the process of manufacture thereof29. As a new article of manufacture, artificial thread silk in which theextensibility due to the precipitation of a cellulose solution in theform of a gel is removed in the process of manufacture thereof to thepoint where the resultant thread is substantially incapable of alongitudinal distortion which would produce rigidity.

30. As a new article of manufacture, artificial silk thread in which theextensibility due to the precipitation of a cellulose solution in theform of a gel is removed in the process of manufacturethereof to thepoint where the resultant thread is substantially incapable of alongitudinal distortion which would alter the refractive index of thatthread in the finished cloth.

31. As a new article of manufacture, artificial silk thread in which theextensibility due to the precipitation of a cellulose solution in theform of a gel is removed in the process of manufacture thereof to thepoint where the resultant thread is substantially incapable of alongitudinal distortion such as will substantially alter the denier sizein the ordinary steps of winding, weaving, etc., on a cotton basis.

32. The process of making artificial silk,

which includes spinning a cellulose solution into a precipitating bath,and stretching the formed thread to the pointwhere it has in thefinished state approximately the same elongation wet as dry, a markedresistance to elongation over a wide range of load, ap proximately thesame elongation for all degrees of relative humidity normally obtaining,and no appreciable yield points in its elongation curve.

33. The process of making cellulose thread which consists in forming thethread, in deflating the thread, in winding the thread on a spool orcylinder, and then in Washing and drying the thread while on the spool.

34:. The method of spinning artificial silk thread which comprisesforming the thread, stretching the thread to largely removeextensibility, and removing water solubles and decopping and deflatingand winding on a spool or cylinder, under suflicient tension to retainthe stretch given in removal of extensibility.

35. The process which comprises forming cellulose thread from individualand non-adherent filaments and in carrying out all subsequent operationssuch as washing and decopping while maintaining the filaments in anon-adhesive condition.

36. The process which comprises forming cellulose thread, in winding andtwisting it on a spool, in removin the spool, and in unwinding thethread therefrom while subjecting it to a washing medium and thereafter,as the unwinding proceeds, drawing the washed thread through a decoppmgsolution, and in winding the decopped thread as drawn on a spool orcylinder.

37. In the manufacture of cellulose thread, the step which comprisesdeflating the formed thread before winding on the washing spool orcylinder to a point such that the thread suffers no material change indimension in the final conditioning thereof, and in winding the deflatedthread.

38. In the manufacture of cellulose thread, the step which comprisesdeflating the formed thread to a point such that the thread suffers nomaterial change in dimension in the final conditioning thereof, and inwinding the thread into a cake and then in washing and drying the cake.

39. The process of spinning, twisting and winding a large amount ofartificial silk thread on a spool of-relatively small diameter whichcomprises spinning the thread;

removing extensibility of the thread to the thread and in winding thethreadon the spool.

The process of spinning, twistinf winding a large amount ot artifieiathread on a sp and silk 001 of relatively small diameter which comprisesspinning the thread removing extensibility of the'thread to the pointthat the thread may be led on to the spool of uniform deniernotwithstanding the change 10 in diameter of the spool, twisting thethread and in winding the thread on the spool under light tension.

In testimony whereof I have hereunto signed my na WILLIAM H. FURNESS.

